Update on tests of the Cen A neutron-emission model of highest energy cosmic rays

We propose that neutron emission from Cen A dominates the cosmic ray sky at the high end of the spectrum. Neutrons that are able to decay generate proton diffusion fronts, whereas those that survive decay produce a spike in the direction of the source. We use recent data reported by the Pierre Auger Collaboration to normalize the injection spectrum and estimate the required luminosity in cosmic rays. We find that such a luminosity, L_{CR} ~ 5 x 10^{40} erg/s, is considerably smaller than the bolometric luminosity of Cen A, L_{bol} ~ 10^{43} erg/s. We compute the incoming current flux density as viewed by an observer on Earth and show that the anisotropy amplitude is in agreement with data at the 1\sigma level. Regardless of the underlying source model, our results indicate that after a decade of data taking the Pierre Auger Observatory will be able to test our proposal.Comment: To be published in PR

Interstellar medium disruption in the Centaurus A group

We present the results of a 21 cm neutral hydrogen (HI) line detection experiment in the direction of 18 low luminosity dwarf galaxies of the Centaurus A group, using the Australia Telescope National Facility 64m Parkes Radio Telescope and the Australia Telescope Compact Array. Five dwarfs have HI masses between M_HI=4x10^5 to M_HI=2.1x10^7 Msol and 0.04<M_HI/L_B<1.81 Msol L_{sol, B}^-1. The other 13 have upper-limits between M_HI<5x10^5 and M_HI<4x10^6 Msol (M_HI}/L_B<0.24 Msol L_{sol, B}^-1). Two of the mixed-morphology dwarfs remain undetected in HI, a situation that is in contrast to that of similar Local Group and Sculptor group objects where all contain significant amounts of neutral gas. There is a discontinuity in the HI properties of Centaurus A group low luminosity dwarfs that is unobserved amongst Sculptor group dwarfs. All objects fainter than M_B=-13 have either M_HI>10^7 Msol or M_HI<10^6 Msol. This gap may be explained by the ram pressure stripping mechanism at work in this dense environment where all galaxies with M_HI<10^7 Msol have been stripped of their gas. The required intergalactic medium density to achieve this is ~10^-3 cm^-3.Comment: 7 figures, 2 table

Avaliação de impacto do Plano BR-163 Sustentável sobre municípios em sua área de influência no Pará/Brasil

Objetivo: Avaliar o impacto do Plano BR-163 Sustentável e identificar a presença de agrupamentos espaciais que expliquem a dinâmica territorial das microrregiões de influência da BR-163. Método: Realizou-se uma avaliação de impacto baseada no modelo Diferenças em Diferenças analisando anos anteriores e posteriores à sua criação. A estratégia empírica adotada baseou-se em: um modelo sem ajustes de pareamento; um com probabilidade inversa ponderada; e um com o pareamento de nearest neighbor. Resultados: Observou-se que a estimativa do efeito da política é positiva e significativa nos três modelos. No primeiro obteve-se o incremento de 1,234% na diferença de desmatamento pós política nos municípios da área de influência da rodovia; no segundo sobe para 1.426% e fica em 1.335% no pareamento de nearest neighbor. Identificou-se que houve desaceleração no avanço do desflorestamento, ponto positivo, porém, não é possível afirmar que este fato decorreu da implementação do plano ou por outras políticas e incentivos municipais e estaduais. Conclusão: A análise de associação espacial realizada evidenciou que as variáveis Desmatamento, Focos de Queimadas e Área de Pastagem podem ser discutidas a nível de agrupamentos espaciais, porém não apresentam tendências semelhantes para toda a área de influência da rodovia.Objective: Evaluate the impact of the Sustainable BR-163 Plan and identify the presence of spatial clusters that explain the territorial dynamics of the micro-regions of influence of the BR-163. Method: An impact assessment was carried out based on the Differences in Differences model, analyzing years before and after its creation. The empirical strategy adopted was based on: a model without matching adjustments; one with weighted inverse probability; and one with the nearest neighbor pairing. Results: It was observed that the estimate of the policy effect is positive and significant in the three models. In the first, there was an increase of 1.234% in the difference in post-policy deforestation in the municipalities in the area of influence of the highway; in the second it rises to 1.426% and stays at 1.335% in the nearest neighbor pairing. It was identified that there was a slowdown in the advance of deforestation, a positive point, however, it is not possible to state that this fact resulted from the implementation of the plan or by other municipal and state policies and incentives. Conclusion: The spatial association analysis carried out showed that the variables Deforestation, Burning Spots and Pasture Area can be discussed at the level of spatial groupings, but do not present similar trends for the entire area of influence of the highway

A Highly Ordered Faraday-Rotation Structure in the Interstellar Medium

We describe a Faraday-rotation structure in the Interstellar Medium detected through polarimetric imaging at 1420 MHz from the Canadian Galactic Plane Survey (CGPS). The structure, at l=91.8, b=-2.5, has an extent of ~2 degree, within which polarization angle varies smoothly over a range of ~100 degree. Polarized intensity also varies smoothly, showing a central peak within an outer shell. This region is in sharp contrast to its surroundings, where low-level chaotic polarization structure occurs on arcminute scales. The Faraday-rotation structure has no counterpart in radio total intensity, and is unrelated to known objects along the line of sight, which include a Lynds Bright Nebula, LBN 416, and the star cluster M39 (NGC7092). It is interpreted as a smooth enhancement of electron density. The absence of a counterpart, either in optical emission or in total intensity, establishes a lower limit to its distance. An upper limit is determined by the strong beam depolarization in this direction. At a probable distance of 350 +/- 50 pc, the size of the object is 10 pc, the enhancement of electron density is 1.7 cm-3, and the mass of ionized gas is 23 M_sun. It has a very smooth internal magnetic field of strength 3 microG, slightly enhanced above the ambient field. G91.8-2.5 is the second such object to be discovered in the CGPS, and it seems likely that such structures are common in the Magneto-Ionic Medium.Comment: 16 pages, 5 figures, ApJ accepte

NOMAD CAMELS: Configurable Application for Measurements, Experiments and Laboratory Systems

NOMAD CAMELS (short: CAMELS) is a configurable, open-source measurement software that records fully self-describing experimental data. It has its origins in the field of experimental physics where a wide variety of measurement instruments are used in frequently changing experimental setups and measurement protocols. CAMELS provides a graphical user interface (GUI) which allows the user to configure experiments without the need of programming skills or deep understanding of instrument communication. CAMELS translates user-defined measurement protocols into stand-alone executable Python code for full transparency of the actual measurement sequences. Existing large-scale, distributed control systems using e.g. EPICS can be natively implemented. CAMELS is designed with focus on full recording of data and metadata. When shared with others, data produced with CAMELS allow full understanding of the measurement and the resulting data in accordance with the FAIR (Findable, Accessible, Interoperable and Re-usable) principles

Active Galactic Nuclei with Starbursts: Sources for Ultra High Energy Cosmic Rays

Ultra high energy cosmic ray events presently show a spectrum, which we interpret here as galactic cosmic rays due to a starburst in the radio galaxy Cen A pushed up in energy by the shock of a relativistic jet. The knee feature and the particles with energy immediately higher in galactic cosmic rays then turn into the bulk of ultra high energy cosmic rays. This entails that all ultra high energy cosmic rays are heavy nuclei. This picture is viable if the majority of the observed ultra high energy events come from the radio galaxy Cen A, and are scattered by intergalactic magnetic fields across most of the sky.Comment: 4 pages, 1 figure, proceedings of "High-Energy Gamma-rays and Neutrinos from Extra-Galactic Sources", Heidelber

New evidence on the origin of the microquasar GRO J1655-40

Aims. Motivated by the new determination of the distance to the microquasar GRO J1655-40 by Foellmi et al. (2006), we conduct a detailed study of the distribution of the atomic and molecular gas, and dust around the open cluster NGC 6242, the possible birth place of the microquasar. The proximity and relative height of the cluster on the galactic disk provides a unique opportunity to study SNR evolution and its possible physical link with microquasar formation. Methods. We search in the interstellar atomic and molecular gas around NGC 6242 for traces that may have been left from a supernova explosion associated to the formation of the black hole in GRO J1655-40. Furthermore, the 60/100 mu IR color is used as a tracer of shocked-heated dust. Results. At the kinematical distance of the cluster the observations have revealed the existence of a HI hole of 1.5*1.5 degrees in diameter and compressed CO material acumulated along the south-eastern internal border of the HI cavity. In this same area, we found extended infrared emission with characteristics of shocked-heated dust. Based on the HI, CO and FIR emissions, we suggest that the cavity in the ISM was produced by a supernova explosion occured within NGC 6242. The lower limit to the kinematic energy transferred by the supernova shock to the surrounding interstellar medium is ~ 10^{49} erg and the atomic and molecular mass displaced to form the cavity of ~ 16.500 solar masses. The lower limit to the time elapsed since the SN explosion is ~ 2.2*10^{5} yr, which is consistent with the time required by GRO J1655-40 to move from the cluster up to its present position. The observations suggest that GRO J1655-40 could have been born inside NGC 6242, being one of the nearest microquasars known so far.Comment: 6 pages, 6 figures. Accepted for publication in Astronomy & Astrophysic

Centaurus A as a source of extragalactic cosmic rays with arrival energies well beyond the GZK cutoff

The ultra--high energy cosmic rays recently detected by several air shower experiments could have an extragalactic origin. In this case, the nearest active galaxy Centaurus A might be the source of the most energetic particles ever detected on Earth. We have used recent radio observations in order to estimate the arrival energy of the protons accelerated by strong shock fronts in the outer parts of this southern radio source. We expect detections corresponding to particles with energies up to $\sim 2.2 \times 10^{21}$ eV and an arrival direction of ($l \approx 310^{\circ}$, $b \approx 20^{\circ}$) in galactic coordinates. The future Southern Hemisphere Pierre Auger Observatory might provide a decisive test for extragalactic models of the origin of the ultra--high energy cosmic rays.Comment: Some remarks by the referee added, to appear in Astroparticle Physic

Sh2-205: II. Its quiescent stellar formation activity

We present a study of active stellar forming regions in the environs of the HII region Sh2-205. The analysis is based on data obtained from point source catalogues and images extracted from 2MASS, MSX, and IRAS surveys. Complementary data are taken from CO survey. The identification of primary candidates to stellar formation activity is made following colour criteria and the correlation with molecular gas emission. A number of stellar formation tracer candidates are projected on two substructures of the HII region: SH148.83-0.67 and SH149.25-0.00. However, the lack of molecular gas related to these structures casts doubts on the nature of the sources. Additional infrared sources may be associated with the HI shell centered at (l,b) = (149\degr 0\arcmin, -1\degr 30\arcmin). The most striking active area was found in connection to the HII region LBN 148.11-0.45, where stellar formation candidates are projected onto molecular gas. The analytical model to the "collect and collapse" process shows that stellar formation activity could have been triggered by the expansion of this HII region.Comment: Accepted for publication in MNRAS, 10 pages, 5 figures, 5 table